In general, the residents of a house lock the front door, extinguish the lighting in the house, confirm that gas appliances are turned off, and similar before leaving the house. However, there are often cases in which one's recollection as to whether the front door was locked or lighting was extinguished is uncertain, and in such cases, there is a desire to confirm the state of affairs after leaving the house.
In such cases, returning to the house to confirm the state of affairs takes time and may incur expenses for transport, and so is a considerable burden on a resident. And in cases in which for example a meeting must be attended at a prescribed time or other work or business appointments must be kept, it may be impractical to return to the house and confirm the state of affairs.
Moreover, there are cases in which one would wish to change the state of the door lock, lighting equipment, gas appliances, or other household equipment of the house. For example, should it become evident that the front door has not been locked, there is a need to lock the door. In such cases, returning to the house to operate equipment incurs similar burdens, and in some cases may not be practical. Moreover, there are cases in which, in mid-summer, there is a desire to start an air conditioner before returning home, to ensure that a room is cool upon one's return home.
In light of such situations, there is a desire to be able to remotely confirm (monitor) the state of household equipment in a house, and to be able to operate the equipment remotely.
On the other hand, there is also a need to effectively prevent remote confirmation of the state of and operation of household equipment by an illicit third party. Hence there is a demand for security enabling only a resident of the house to remotely monitor and operate household equipment, without allowing a third party to perform such actions.